summer dormancy (was Blue bulb and similar)

Sun, 14 Aug 2011 02:42:11 PDT
Hello Peter,
A very concise and  clear explanation. This also explains why in some cases 
typically mediterranean bulbs (such as Crocus) are grown in a  cooler climat 
(per example  UK or  the Neherlands) produce a much better size because of 
the long  springtime growing period.  When here  the leaves are drying off 
in April, in Holland the growth goes on until early June. Of course  in the 
Dutch climat the growers have to make some artificial arrangements to  
obtain  warm and dry summer conditions.

Kind regards
Lauw de Jager 
South of France

-----Original Message-----
Temperate continental climate bulbs basically root following rain and/ or
fluctuating temperatures before winter, they may then slow down, while
frozen, untill thawing/ snowmelt/ spring time. They then go dormant for a
(hot) dry period in summer which stimulates the setting of flowerbuds within
the bulb. The cycle is started again by fluctuating / cooler night
temperatures and water before winter. If they dont get enough cold in
winter, the embryonic flowerbuds will not have time to develop before
spring, and I would expect lots of leaf instead and aborted flowers. Alpine
houses are often kept frost free in the uk, and this is fine for these
bulbs. The winter cold dormancy after rooting and before top growth is
enforced by giving only a very little water untill top growth is required. I
expect that the biggest problems you might encounter in a hotter climate is
that when the bulbs get warm they must be allowed to go dormant (and dry) or
they will rot. This may be before they have finished a full seasons growth
resulting in poor bulbs for the following year. I think keeping them cool to
achieve a long spring growth period 

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